Recently, standardization of Long Term Evolution (LTE) as a technical standard developed further than 3GPP has been in progress. LTE has required a radio communication scheme with larger capacity and higher speed, and optimization of a radio source assignment control in accordance with a communication performance and service of a user terminal (UE).
Plural different carrier frequencies and signal bandwidths are defined throughout a network in LTE, which makes it possible to use different frequency layers in an overlapping way even in the same geographical area. In addition, different user terminals having different communication capabilities (UE capabilities) are allowed in the network.
In order to maintain a throughput while allowing an increase in user capacity, load balancing is indispensable between the frequency layers. It has been proposed to redirect (change over) a cell (carrier) to which the user terminal is connected to an appropriate cell (carrier) at the time of establishing RRC in order to carry out appropriate load balancing (see “Multi-band/carrier operation (2)—Load Balancing”, 3GPP TSG RAN WG2 #54, R2-062172, 28th August to 1st September, Tallinn, Estonia, for example).